1. Field of the Invention
An embodiment of the present invention relates to an image diagnosis apparatus.
2. Description of the Related Art
An MRI (Magnetic Resonance Imaging) apparatus is one of image diagnosis apparatuses used in a medical field, and a related imaging method is diffusion imaging. The diffusion imaging is a method for taking a diffusion weighted image (DWI) which emphasizes a diffusion effect such that particles such as water molecules diffuse owing to thermodynamic Brownian motion. The diffusion imaging draws attention as being useful for early diagnosis of cerebral infarction.
Further, the diffusion imaging develops as diffusion tensor imaging (DTI) in a cerebral nerve area in which anisotropy of nerve fibers is detected or nerve fibers are depicted with the use of anisotropy. While diffusion imaging produces a two-dimensional monochrome image as usual, DTI produces a two-dimensional color image.
Further, an imaging method called “diffusion tensor tractography (DTT)” draws attention as well in recent years. According to DTT, a maximum diffusion direction is tracked, e.g., on a voxel basis or on a slightly expanded voxel basis on the basis of a diffusion tensor image (called a DTI image hereafter) obtained owing to DTI, a trajectory of the tracking is depicted three-dimensionally, and a diffusion tensor tractography image (called a DTT image hereafter) is generated.
Incidentally, technologies including volume rendering, DTT described above and vector flow imaging are known as a method for indicating three-dimensionally linear (line shape) information obtained by the aforementioned MRI apparatus and X ray CT apparatus such as a cerebral blood vessel, a bundle of nerve fibers or blood flow velocity.
Further, as to images of three-dimensionally indicated line shape information, such images of a same patient's same part in time of the onset of a disease and of a study after a medical treatment are arranged side by side, so that a user visually observes the images so as to check an effect of the medical treatment.
A related art is disclosed in Japanese Unexamined Patent Publication No. 2009-148314.
As information density of the line shape information is so high that its indication is complicated, though, it is difficult to visually observe in the case of a tiny change. Thus, in conventional technique, an index indicating a degree of the disease (called an abnormality degree, hereafter) cannot be observed in perspective from a difference between the images in time of the onset of the diseased part and the images in normal condition. Further, there used to be no objective index which indicates to what extent the condition has recovered (called a recovery degree, hereafter) between the images in time of the onset of the diseased part and the images in time of a study while or after being treated.